The present invention is related to a method and arrangement for limiting the use of a mobile telephone.
In modern mobile telephone systems, a subscriber has a SIM card (Subscriber Identification Module). Data contained in the SIM card identifies the subscriber, and in practice, the data is used to check the user rights of the subscriber each time he or she uses the services of the system. By using the SIM card, the subscriber can use any mobile telephone that operates in the system. If no arrangement existed by which misuse could be prevented, then, for example, stolen mobile telephones would be easy to use by anyone possessing a SIM card. Therefore, for example, in the GSM system, an international mobile equipment indentification code, IMEI, is stored in a permanent memory location in each mobile telephone. The intent is that operators maintain a corresponding equipment identification register, EIR, which contains a list of the equipment identification codes of stolen telephones, for example. In certain situations, the system checks the equipment identification code of the mobile telephone and compares it with the data in the equipment register. If said equipment is listed as stolen, the system should block its use. In the example GSM system, which is used quite broadly, it has not yet been possible to satisfactorily implement such a checking system. The equipment registers of the operators and the data contained therein are incomplete, and it is not possible in all networks to prevent the use of a stolen mobile telephone, even if it were noticed that it is stolen. Because the inadequacy of the system that prevents misuse is known by many people, mobile telephones are commonly stolen and misused. The thefts are especially directed towards rented telephones, which are rented under false names expressly for this reason. Because the GSM system and the amount of mobile telephones used in the system are continuously growing rapidly, it is probable that these problems will also exist in the future.